CFD Simulation and Analysis of LOHC Dehydrogenation Furnace and Reactor Configurations

The LOHC dehydrogenation furnace and reactor are simulated in the present work to produce 10 N m3/h of hydrogen. Two reactor configurations are considered for the LOHC dehydrogenation system–helical and U-tube coil configuration. The furnace model is validated by comparing model predictions with the steam-cracking furnace simulation from Habibi et al. (Impact of Radiation Models in CFD Simulations of Steam Cracking Furnaces. Comput Chem Eng 2007, 31 (11), 1389–1406. https://doi.org/10.1016/j.compchemeng.2006.11.009.). The flue gas temperature distribution, velocity, heat flux, and wall temperature within the furnace are determined by solving the mass, momentum, and energy equations through simulations conducted in Ansys Fluent software. The wall temperature obtained from the CFD simulation is used as an input for the 1D model of the dehydrogenation reactor to obtain the process side temperature and perhydro dibenzyltoluene (PDBT) conversion along the reactor length for both configurations. The reactor is designed to achieve more than 99% conversion of perhydro dibenzyl toluene. The wall temperature along the reactor length varies linearly from 660 to 807 K for the helical coil configuration, whereas the wall temperature for the U-tube configuration varies sinusoidally along the reactor length between 670 and 817 K. Additionally, the high wall temperature reduces the length required for the helical and U-tube coil configurations to achieve 99% conversion, compared to the constant wall temperature conditions reported in previous literature (Rao et al., Optimization of Liquid Organic Hydrogen Carrier (LOHC) Dehydrogenation System. Int J Hydrogen Energy 2022, 47 (66), 28530–28547. https://doi.org/10.1016/j.ijhydene.2022.06.197). The helical coil configuration also demonstrates slightly higher thermal efficiency across various conversions compared to the U-tube configuration, offering valuable insights for designing efficient LOHC dehydrogenation systems.